• Toxicological Research
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• v.8 no.1
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• pp.9-15
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• 1992

Hydroxybrazilin was examined for its effects on glycogen synthesis in primary cultured rat hepatocytes. At 10-6 M hydroxybrazilin, glycogen synthesis was increased in basal state, but not in insulin stimulated state. However, any signiFicant changes were nor observed at 10-5 M hydroxybrazilin in both states. The glycogen synthesis was rather suppressed at 10-5M hydroxybrazilin. It was also observed that hydroxybrazilin increased insulin sensitivity but not insulin responsiveness at 10-5M concentration. These results suggest that hydroxybrazilin might exert hypoglycemic action through its effects on insulin receptor and post receptor events.

• Environmental Analysis Health and Toxicology
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• v.11 no.3_4
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• pp.53-57
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• 1996

In this study we investigated the effect of hydroxybrazilin on glutathione depletion induced by BrCCl$_3$ and menadione in cultured hepatocytes to understand the cellular mechanisms of hepatoprotective effect of hydroxybrazilin. Hydroxybrazilin alone had no effect on total glutathione level and the ratio of reduced glutathione/total glutathione (GSH/(GSSG+GSH)). BrCCl$_3$ dramatically decreased total glutathione level and hydroxybrazilin significantly prevented glutathion depletion by BrCCl$_3$. The ratio of GSH/(GSSG+ GSH) was also decreased by BrCCl$_3$ and recovered by hydroxybrazilin treatment. Menadione decreased total glutathione level and the ratio of GSH/(GSSG+GSH) but hydroxybrazilin showed no significant effects on menadione-induced glutathione depletion. These data suggest that hydroxybrazilin might prevent the hepatotoxicity induced by chemicalderived radicals but not the toxicity linked with oxidative stress.

• YAKHAK HOEJI
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• v.38 no.1
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• pp.97-101
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• 1994

Platelets play a very important role in nomal hemostasis and their functions are more enhanced in various pathogenic states than in normal state. Especially it has been postulated that abnormal platelet and endothelium function might be major factors of microcirculatory disturbance in diabetes mellitus. Hydroxybrazilin, a phenolic constituent of Hematoxylon campechianum has been examined for its inhibitory effect on platelet aggregation. Its antiaggregatory effect might be mediated through the decrease of ATP release from dense granule and those of thromboxane $A_2$ production in normal and streptozotocin induced diabetic rats. The present study was undertaken to gain insight into the mechanism that hydroxybrazilin inhibited thromboxane $A_2$ production in platelets. Thus we measured the effect of hydroxybrazilin on phospholipase $A_2$, a rate limiting step of thromboxane $A_2$ production, in normal and streptozotocin induced diabetic rats. Hydroxybrazilin significantly inhibited the platelet phospholipase $A_2$ activity in normal and streptozotocin induced diabetic rats.